On the HD, I wanted to keep the stock radio, but wanted my sub wired in to it. Since the OEM HU's don't have a RCA patch, you need to obtain a line out converter to adapt the speaker level outputs to the regular line level input on sub amps (will sound bad if you don't have that).

Tools
Butter knife (to remove the dash facia)
Quick tap connectors
Pliers
Wire cutters
Screwdriver/hex driver (depending on style of amp wire hold down connections)
Zip ties
Wire hold down

Supplies
8 gauge or 4 gauge wire (depending on the amp). 15 feet. 2 colors are suggested for positive/negative cables.
80 amp fuse holder and fuse
15 feet of 14 gauge wire (Streetwires has a kit available that contains amp wiring, suggest getting a kit)
Line out converter (available at Cartoys, Best Buy, ebay) Suggest a good 2 channel.
2 gauge negative battery cable
Amp
Sub

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UNHOOK THE BATTERY CABLES FROM THE BATTERY!


LINE OUT CONVERTER INSTALL:

1. Pull apart dash and radio. Follow the instructions in the Wiki 2007-2009 HD Dash / Radio Removal. I used a butter knife to pull the facia apart.

2. Pull the radio from the dash and disconnect the wiring harness.

3. On the harness, there are several wires you need to tap into. The plug itself is a way to determine the wire identifiers, or what each wire does. As you look at the plug with the tab on the top, (plug end, not wire end), the ETM has each pin numbered from right to left ands top to bottom. #1 is at the top right pin and each pin next to it is numbered 2,3,4 etc. You will need to pay close attention to each wire and tap into the ones you need to tap into. I suggest using a quick connector to avoid splicing wires.

4. On the LOC, there should be instructions on which wire goes to the radio harness. The one I got did not have a 12VDC battery power. The instructions that come with the unit will tell you to tap into a positive and negative speaker lead. The unit must be hooked up so the positive lead on the LOC is wired to the positive lead on the speaker output on the harness and the same with the negative lead.

On the harness, you will need to tap into the positive rear speaker wire, which is pin 3 for the right speaker and pin 4 on the left speaker. The negative wires you need to tap into is pin 15 for the right speaker and pin 16 for the left speaker. The LOC should be completely wired up at that point. If you are using a powered LOC, you need to use pin 11 for power (same one for the amp remote lead and pin 24 for ground.

HINT: You also need to connect the amp remote wire to the same harness. It is best if you do that while you are in there. Pin 11 is the switched power supply to the radio. Another possibility is to use the aux power outlet power, which is also switched for the remote lead power source. You also will need to hook up the RCA patch to the LOC as well. I fished the remote lead from the drivers side and the RCA patch cord on the passenger side of the dash panel to separate the 2 audio/power systems (can create noise issues if you have them together).

5. Ziptie the LOC and the wiring together without pulling apart the wires.

6. Hook up the main harness to the radio and reinstall radio and replace dash facia.

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AMP INSTALL:

Now the wires are installed in the back of the radio, you will need to finish up with the amp install..

7. Remove the plastic kick panels and lower panels below the doors and the B pillar on both sides of the car.

8. You will need to fold the rear seat back down on both sides to fish the wiring to the trunk. Seat bottom removal is optional, but makews it easier to place wires in their location easier. I did not remove the seat bottom.

9. Temporary place the amp remote wire and the RCA patch in the channels where the factory harness is located. and route them to the trunk area, but leave them loose at that point.

10. For the amp positive power wire, I drilled a separate hole for that and used a grommet to hold the wire. There should be grommets available on the drivers side by the firewall behind the front kick panel if you want to go that route. That may involve removing the drivers side front wheel well panel though. Fish the wire through the firewall and leave enough slack to get to the battery and route that in the same location as the amp remote lead. It is best to leave more wire out front because you don't want that to be too tight.

11. Wire tie the newly laid wires to the main harnesses on each side and replace plastic panels.

12. Screw the amp to the rear seat back. It is best to do this where the wiring is easy to get to and won't interfere with the seat being pulled down frequently.

13. Route the wires to the amp and wire tie the wiring together at the back of the seat using a wire clip that screws to the back of the seat. Leave enough slack to allow movement of the seat.

14. Attach a short piece of wire (negative cable) to the body of the car that is close to the amp. The fuel tank is close by, so you might want to attach it to a place that is close to the bottom of the panel separating the trunk from the interior of the car with a screw/small self tapping bolt. I used a eye hole wire end for this.

15. Hook wires up to their location on the amp.

16. Under the hood, attach the inline fuse no more than 7 inches from the battery to the wire you put through the firewall and hook that to the positive lead to the battery.

17. Remove the negative battery cable from the chassis and replace that with a 2 gauge battery cable and reattach that to the battery.